Process of utilizing acid sludge



Patented Jan. 10, 1950 2,494,420 P'Rocis'ss F UTIniIjzING ACID SLUDGE ii-Joseph Hf'Wells and Philip J. Wilson, Jr., Pittsburgh, Pa., assignors'to Carnegie-Illinois Steel Corporation, afcorpor'ationof'New Jersey ZCIQLimS. (Cl. 75-3) ATENT OFFICE t"; 1 'Ifhis inv ntion relate to therocess ofiitilizns the a d-.. l1ds Whi f sirrdduc das a'j y- L product,in the vti"eatmjfllantfof j'c'oke 'o'y'en j.light oil,

or lower boiling coal'tar "fractionsfiwith c'o'ncentratedsulfuric}'acid,',"andfisf a 'continuationin- 5 partjfof ourc'o'iiehdi'ngffapplication SeriaFNo, 507,834, filed. October' 27,1943;now abandoned. 7 The crudelightoilobtairiedifrom coke oy'eirg'as isfirst {distilledto fren 'ove the reSidue. In some j cases, thefractionation may f'include j removal 'o'f'fore'r'unnin'gs boilingbelow80 c..' The distilled light oil is then washed with twdj'to' jfour,v percent by volume of60 to 66 B. sulfuiicfacid in AQld Sllldggjljqm therefining of avertical[cylindricalitank' equipped'with a stirfrer. Theoil' and acid "aremixed at apprfoxk niately room. temperaturefuntil the're'acti0nbetween the acid and the impurities has proceeded 's'uificient1y far to insurettheii' remdval from the oil. .Water'may thenb'eadded'in a volume equal to one or two times ,the volumefof sulfuric acidused, but in nocase should .the'amount of water I added be such thatjtheconcentration 'of'the acid in the agitator tank-be reduced below sul-Qfuric acid. The agitation} is thenfstopped-and the acid andsludgelayersfwhichsettle below the oil layer are drawn off. Thesludgelayeriisonly slightly soluble in and separates quite,;rapidly fromsulfuric; acid solutions greater in strength ntbe a duc ed. m s i'utilieithe "orgia fi" a elbe nimade "i us fa ablnde uettes of oreiortylirnakesco'atith a hin; junifojrni ar eiamount 'oiri'the or anic n30%,su1r i a id. i'rh .s u igei i r ,iewahfarjer. saturated and,sulfur;'COniDGHnGSQf Qm MTO QTb T T'W 1J'f im at .Q di einassjivhenflheatedto a which condense, -p erize, and'otherwiserea'ct t'OfiC.

with themselves an 7 ith the sulfuric acid to ,1'llh epresent'inventionisi liasediupon the disproduce a reddish brown, resinous, sticky mass,bov'erythaflthe r'es'ir'rousorganic matter, which which is often ratherviscous d ip thi is referred to hereinafter by the term acid resin, massis a large proportion of sulfuric anawmeh; "in" the" sludge may beutilized successfully as a although it has promoted; the .a therreactions, a,-binder,forvarioustypes of solids when it is hanhas stillnot itself reacted. The sludge also condled'in the-following manner:tains a certain proportion of theaoil entrained r'Iheacid sludge isdischarged as produced into or dissolved in it. p a separator ordecanter, and allowed to remain The above description indicates thatthis acid i d-therein until' the acid resin has separated into a sludgeis a material whichj is difiicult --to-handle layenabove thefaqueoussolution of sulfuric acid. and which presentssubstantiali-disposalproblems. smallamountsot acid resin may beentrained or A number of processes have been-developed-for -dissol-vedin-theacid, and vice versa. The two recovering the free sulfuricacid-whichit -c0n- -=-layersare separated, and the acid layer may betains. In some of these -;'-processes-the-sludgeheated to s'epar'ate anyacid resin left. The small is heated, which causes-the erganic matteraoamount of=pitch thus produced is discarded since polymerize or coagulateand to rise to--the-top the-characterof the acid resin is so altered bythe of the resulting dilute sulfuric-acid "solution-as a -heatingoperationthat it is no longer of value for highly viscous, black pitch.The acid-isdrained J @thepurpose of this invention. away and the pitchis discarded by ,whatever ,;.50 Afterdecantation, the acid resin isthinned means are least objectionable," whichis 'usnally I with waterfsothatit will flow readily and proon a dump or by burning. duce a uniform;thin film on a solid surface. The In other processes, the sludge isneutralized volume of water used may amount to one or two with analkali, such as ammonia, which reacts times the volume of acid resin, oreven more. In with the acid to produce ammonium sulfate. The case theacid in the acid resin injures the solids,

a neutralizing agent may be added at this stage. The acid resin solutionthen is applied to the solid surfaces, either by mixing the twotogether, or by spraying, or distributing it in any other briquettes,and the latter finally baked at 100 C. for 1.5 hours. After cooling, thebriquettes were tested for compression in an Amsler testing machine.

Acid Rwin from Acid Pounds of 535 3 255 Character 523551 2? itttti$01335? pett ttd from sludge iitst tid Finished per cent by volume FlueDust fifgfgfig Binder Mix g gggg i manner. The coated materials arepressed to gether firmly, and as a final step, the moisture isevaporated by heating or by exposure to the atmosphere.

The process may be operated either continuously or as abatch process; orcertain portions may be continuous and the balance batch.

The utilization of acid resin is exemplified in the briquetting of fluedust recovered during operation of a blast furnace producingferromanganese. Such flue dust contains considerable manganese, so thatit may not be discarded, in view of the strategic importance ofmanganese. Such dust cannot be recharged into the furnace,

' because a large portion would be blown out from the furnace a secondtime, and also because such dust might interfere with furnace operation.a

While flue dust from a blast furnace using iron ore may be sintered,that from a ferro-manganese furnace will not slnter. However, it isfound in accordance with the present invention, that the acid resinproduced from. the acid sludge by the present process can be utilized toproduce briquettes of this fine ferro-manganese dust of sufficientstrength for recharging into the furnace. Also, it is found bycontrolling the proportions of materials, that alkali in the flue dustwill neutralize the acid in the binder, and the resulting briquetteswill not corrode steel equipment when wetted.

The following table shows tests on the production of briquettes ofapproximately 2.5 centimeters in diameter by 1.1 centimeters high,containing different proportions of binder. The flue dust from the drydust catcher of a ferro-manganese furnace was pugged with the binderuntil uniformly wetted, the mixture compressed into The above tableshows that it is possible to secure briquettes of excellent strength bythe use of acid resins highly thinned with water. The strength of thebriquettes is not a function of the quantity of binder, and excellentbriquettes may be produced by the use of very small amounts of acidresin as long as the resin is completely and uniformly distributed overthe surface.

The briquettes withstood heating to a red heat without disintegrating orlosing their shape, which is advantageous for their subsequent exposureto high temperatures and severe mechanical action which are present inthe blast furnace.

The acid resin can be used in a similar manner for preparation ofbriquettes from coal, coke, sawdust, and other solids and for otheradhesive purposes.

We claim:

1. The process of preparing briquettes of blast furnace flue dust, whichcomprises combiningwith flu dust a resinous acid sludge obtained bytreating coke oven light oil with to 66 Be. sulfuric acid, allowing theresulting sludge and acid to settle into layers, separating the sludgefrom the acid, thinning the. said sludge with at least an equal amountof water until it flows readily. and adding the resulting thinned sludgeto the flue dust and mixing therewith thereby producing a uniform, thinfilm on the thinned sludge of the said flue dust, thereafter pressingthe resulting coated material firmly together, and evaporating themoisture contained therein.

2. The process as claimed in claim 1, wherein the flue dust to bebriquetted is flue dust from a blast furnace producing ferro-manganese.

JOSEPH H. WELLS. PHILIP J. WILSON, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name a Date 987,554 Coggeshall Mar. 21,1911 1,059,150 Haage Apr. 15, 1913 1,521,283 Diggs Dec. 30, 19241,655,728 Johnston et al Jan. 10, 1928 1,680,107 Marquard Aug. 7, 19281,749,378 Goodwin Mar. 4, 1930 1,872,463 Jones Aug. 16, 1932 2,164,950Schulze July 4, 1939 OTHER REFERENCES Briquetting" by Stillman,published by the Chemical Publishing 00., 1923, page 402.

1. THE PROCESS OF PREPARING BRQUETTES OF BLAST FURNACE FLUE DUST, WHICHCOMPRISES COMBINING WITH FLUE DUST A RESINOUS ACID SLUDGE OBTAINED BYTREATING COKE OVEN LIGHT OIL WITH 60* TO 66* BE. SULFURIC ACID, ALLOWINGTHE RESULTING SLUDGE AND ACID TO SETTLE INTO LAYERS, SEPARATING THESLUDGE FROM THE ACID, THINNING THE SAID SLUDGE WITH AT LEAST AN EQUALAMOUNT OF WATER UNTIL IT FLOWS READILY AND ADDING THE RESULTING THINNEDSLUDGE TO THE FLUE DUST AND MIXING THEREWITH THEREBY PRODUCING AUNIFORM, THIN FILM ON THE THINNED SLUDGE OF THE SAID FLUE DUST,THEREAFTER PRESSING THE RESULTING COATED MATERIAL FIRMLY TOGETHER, ANDEVAPORATING THE MOISTURE CONTAINED THEREIN.